Failure to launch

Hi, I have a device with a standalone 328. Previously, I have used this for data gathering. I wrote a sketch which took readings from sensors on A/D inputs A0 to A5. Then I tried a different circuit: to measure the voltage of a battery connected to A0. The battery is 4 NiCads. Nominally this is 4V8, but, when freshly charged, the battery is nearer 5V6. I did try to 'drop' 1/2 volt using a diode, but made a hash of it and I think I may have tempororily connected 5V6 to pin A0. Anyway, I have tried many times to upload a new sketch to this 328, but the existing sketch refuses to budge ( although it still works OK ). The IDE reports a successful upload each time, but the new sketch doesnt load in reality. Is this odd behaviour what one might expect if the chip has been damaged. And would 5V6 on A0 be expected to wreck the chip?


That's odd. You may have damaged it. Which method are you using to upload the sketches?


Have you tried to get it to do something completely trivial and obvious like upload and run 'blink' showing an LED on D13?


Hi, yes and yes. I'm using the same upload method as was perfectly reliable before and I have tried to upload the 'Blink' sketch. Same negative result. Would 5V5 on A0 be expected to damage the chip? I guess I had better try substituting another 328


poriet: Would 5V5 on A0 be expected to damage the chip?

The answer would be a definite "maybe". In electronics in general, sometimes you can push the rating extremes by around 5% to 10% without significant issues. However, you should never count being able to do this! The only guarentee for not doing any harm is to stay within the manufacturer's ratings.

I got another 328 and ( after burning the bootloader ) programmed that. It seems to work, so we assume the original chip is U/S.

Thaks again bruce